Under some circumstances, it is desirable to be able to kill only selected plants during weeding, thinning, or the like, and/or to provide for the supply of plant-killing electricity only in particular areas. Additionally, there are situations when the supply of plant-treating liquids is desired in combination with electric destruction of plants. The present invention provides a structure suitable in all of the above situations, the present invention applying high potential electrically conductive liquid onto plants for transferring electricity from a high voltage source to ground through plants that are sprayed.
The basic concept of applying electrically conductive liquid for plant destruction is old, as taught by U.S. Pat. No. 2,558,376. However, heretofore such systems have been designed only for the continuous application of liquid to plants, or to the ground, contain electrically charged movable parts, and are not readily adaptable for commercial operations. Additionally, prior art proposals are susceptible to burnup of the high voltage source, and have limited flexibility.
According to the present invention, a machine for destroying plants with electricity is provided which is very versatile, being utilizable for a large number of plant-killing operations aside from mere broadcast destruction, contains no electrically charged movable parts, can readily electrically isolate the electrically conductive liquid from the rest of the machine, and has provisions for positively preventing high voltage source burnup.
According to the present invention, a machine is provided for destroying plants with electricity which comprises a tank adapted to hold electrically conductive liquid therein; means for placing the conductive liquid in the tank at high electric potential, including a high voltage source of electricity; nozzle means for spraying high potential electrically conductive liquid on plants to be destroyed for transferring electricity from the high voltage source to ground through plants sprayed thereby; and means for grounding the high voltage source. Preferably means are further provided for selectively supplying liquid from the tank to the nozzle means, and condition responsive means--responsive to plant position--can control the selective supply means. The selective supply means preferably comprise pneumatically operated valves in each conductive liquid line for each nozzle. The same air pressure source which is used to operate the pneumatically operated valves also preferably provides air under pressure at the top of the liquid in the conductive liquid tank to provide a pumping action, and also provides the source for a fluid proximity switch which is responsive to plant position for controlling operation of a pneumatically operated valve. Means are also provided for limiting the current output of the high voltage source so that damage thereto is prevented, as well as means for controlling the no-load voltage of the high voltage source to a maximum level.
By utilizing the machine according to the present invention, crop thinning, broadcast destruction of plants, weed thinning with minimum energy comsumption, and combination herbicide and electric treatment or fertilizer and electric treatment are provided for.
It is the primary object of the present invention to provide a versatile machine for destroying plants with high potential electrically conductive liquid. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.